Effect of sample preparation and characterization methods on quantification of non-metallic inclusions in NiTinol products

Material Specification for Nitinol products used for medical applications is defined per ASTM F2063. While the ASTM standard specifies acceptable maximum porosity and nonmetallic inclusion size and area fraction, it does not define the sample preparation or test method to evaluate these. In the present study, the effects of sample preparation (as-polished vs as-etched) on the non-metallic inclusion geometry, dimensions and area fraction will be investigated. For this study, high purity alloy in hot worked condition with section size of 0.5 inch or 1 inch will be used. The samples will be characterized using scanning electron microscope in backscattered electron imaging mode along the hot-work direction (longitudinal). The effect of mounting material (i.e. conductive vs non-conductive) on non-metallic inclusions statistics will be also examined.